A comparative study of laser- and electric-field-induced effects on the crystallinity, surface morphology and plasmon resonance of indium and gold thin films

The effects of post deposition treatment of In and Au thin films by excimer laser and electric field are reported. The films were subjected to an electric field in the range of 0.1-3.3 kV/cm and laser irradiation in the range from 0.01 to 0.0 J/cm(2). The effect of this treatment on the morphology and crystallinity of indium and gold thin films (10-100 nm thickness) is investigated Indium films exhibited a three-fold grain growth at an electric field of 3.3 kV/cm. Gold thin film, on the other hand, showed significant grain growth at a much lower field of 0.6 kV/cm. The as deposited thin films of indium and gold were amorphous but turned nanocrystalline with average crystallite sizes of 57 nm at 3.33 kV/cm and 35 nm at 0.66 kV/cm, respectively. When indium thin films were laser irradiated, flat disc-shaped grains for as-deposited thin films were transformed to spherical grains at a laser fluence of 0.02 J/cm(2) and cubical grains at 0.05 J/cm(2). At 0.05 J/cm(2), as-deposited amorphous indium and gold thin films turned nanocrystalline with crystallite sizes of 50 nm and 10 nm respectively. Significantly, laser treatment causes the grain-size distribution to become narrower with a shift in mean size to larger values. Electric-field treatment on the other hand leads to a shifting of the mean grain size to larger values without affecting the distribution.